Importance

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Abstract

In renovating an existing underground pipe with a new metal pipe installed inside the underground pipe, the invention provides a method of repairing the existing underground pipe characterized by transporting a metal tubular material as wound up in the form of a roll to a repair site, the tubular material being deformed to a flat folded form so as to be diminished in effective outside diameter and to be restorable to a metal pipe of an outside diameter corresponding to the inside diameter of the underground pipe when inflated by application of pressure from inside, installing the roll of tubular material on the ground, subsequently inserting the tubular material into the underground pipe through an underground work pit while unwinding the tubular material from the roll, closing opposite ends of the inserted portion of the tubular material, and thereafter restoring the closed portion of the tubular material to a metal pipe of circular cross section by applying pressure thereto from inside with a pressure fluid. Thus, the metal pipe can be installed inside the existing underground pipe efficiently without necessitating a large work space inside the work pit.

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First Claim